Equipment

Item Drops

Attack Patterns

Fires crossbow bolts when you are within range, also when hidden by her Thief's Ring.

Switches to Baby's Nail and Buckler shield up close. Keeps her shield up, and is also quick to recover after you block her.

Parries?

Strategy

Board & Sword

Approach with your shield raised and lock on. Try to dodge the bolts rather than deflecting them. Avoid running straight at her. Once she fires try to close the distance as quickly as possible. Get in two or three hits while she is reloading and then retreat with your shield raised. Repeat.

Once her health is depleted to 50% or so, she will start to come after you melee only. Retreat all the way back to the ballista with your shield raised. When you reach the ballista, she will then retreat and switch back to the crossbow. Repeat the tactic above to catch her during reload.

Fire Spray

Have Fire Spray handy when fighting. You can easily sidestep the crossbow bolts and continuously attack without worry. If the BP starts melee attacks, retreat to the ballista and repeat method until you win. In NG+, magic enhancements like Kris Blade and Ring of Magical Sharpness will help, and you will most likely need spice for mp.

Poison Cloud

If you have Poison Cloud, this fight can be considerably easier. Having a 100% damage reduction shield here also helps a lot, but isn't completely necessary. Have Poison Cloud ready to go as you ascend the stairs. When she starts firing, block a few to get the timing right. You should have just enough time to get the spell off between her crossbow bolts. Because of its short range, you might wind up putting her into melee range before you can hit her. Once you do get her into the cloud, just evade and wait out its damage. It should take 2 clouds to finish her off.